The invention relates to a process for treating water using ozone.
If ozone is used during treatment of table water and mineral water, as well as drinking water, the problem arises that bromides contained in the water are partly oxidized by the ozone to bromate; bromates are regarded to be noxious. Though there are at present no limits for a content of bromate in water, it is known that bromates in a higher concentration may be carcinogenic.
The formation of bromate ions by ozonizing bromide-containing water is known. It is further known that the bromate formation under a constant concentration of ozone in water largely depends on the pH value of the water. See e.g., U. von Gunten and J. Hoigne, J. Water SRT-Aqua 41 (5): 299-304, 1992, Factors Controlling the Formation of Bromate Ion during Ozonation of Bromide-containing Waters. In this publication there is further on given the hint that ammonia may lead to formation of monobromamine which is subsequently further oxidized to nitrate and bromide ions. It is suggested to get rid of the bromate problem by adding ammonia. Addition of ammonia, however, influences the quality of the water and there are legal limits to be respected.